> -----Original Message----- > From: iommu-bounces@xxxxxxxxxxxxxxxxxxxxxxxxxx [mailto:iommu- > bounces@xxxxxxxxxxxxxxxxxxxxxxxxxx] On Behalf Of Hiroshi Doyu > Sent: Thursday, August 14, 2014 12:18 PM > To: Thierry Reding; Stephen Warren; Arnd Bergmann; Will Deacon > Cc: Mark Rutland; devicetree@xxxxxxxxxxxxxxx; Olof Johansson; > iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx; Rob Herring; linux-tegra@xxxxxxxxxxxxxxx; > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > Subject: Re: [PATCH v5] devicetree: Add generic IOMMU device tree bindings > > > Thierry Reding <thierry.reding@xxxxxxxxx> writes: > > > +Multiple-master IOMMU: > > +---------------------- > > + > > + iommu { > > + /* the specifier represents the ID of the master */ > > + #iommu-cells = <1>; > > + }; > > + > > + master@1 { > > + /* device has master ID 42 in the IOMMU */ > > + iommus = <&{/iommu} 42>; > > + }; > > + > > + master@2 { > > + /* device has master IDs 23 and 24 in the IOMMU */ > > + iommus = <&{/iommu} 23>, <&{/iommu} 24>; > > + }; > > I think that this "master ID" will be parsed in IOMMU driver. For example, > ARM,SMMU expects "streamID" as "master ID", right? > > If a SoC has a feature to configure to assign streamID to devices at runtime, > "streamID" is not equal to "master ID". > > iommus = <&{/smmu} "soc specific master ID">; > > "soc master ID" needs to be translated into "streamID" by SoC SW. It seems > that ARM,SMMU kernel driver doesn't expect this kind of ID translation. If > ARM,SMMU kernel driver is used as is, "soc master ID" > would be incompatible? ARM,SMMU needs such translation before parsing. Is > this my understanding right? > > If so I think that this master ID configuration/translation may be quite > reasonable requirment for SoC using ARM,SMMU. > > Can we consider this ID translation within ARM,SMMU compatibility? > > IOW, is it possible to implement some SoC specific hook for ID > translation/configuration in ARM,SMMU kernel driver? Can the id translation be done using a SMR mask? Also, for dynamic stream ID allocation we would need to represent the specific master register (to store the stream ID) in the device tree. -Varun -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
